Method and flux composition for treating uranium



United States Patet METHOD AND FLUX COMPOSITION FOR TREATING URANIUM Frank Foote, Chicago, Ill., assignor to the United States of America as represented by the United States Atomic Energy Commission No Drawing. Application December 3, 1345 Serial No. 632,599

3 Claims. (Cl. 7584) The present invention relates to protective fluxes and is particularly concerned with providing protective fluxes for the melting of uranium and alloys of uranium.

In the past, several fluxes or mixtures of flux materials have been used for the protection of molten metals in order to prevent surface oxidation or to hinder the volatilization of low melting point metals during alloying processes. Certain fundamental requisites must be met by this type of flux. For example, it must have a melting point considerably below that of the metal and its alloys. At the same time the flux must have the proper specific gravity and surface tension in order to float on the metal or alloy when in molten condition and at the same time cover the same with an inert protective film, in order to prevent undue oxidation thereof, and also to prevent volatilization of the metal and its alloys. In addition there must, of course, be no chemical reaction between the flux and the metal or its alloys. Very few fluxes meet all of the foregoing requirements, the majority being ruled out because they react with the metal or do not have the required combination of specific gravity and surface tension to prevent surface oxidation or volatilization. The problem of securing a suitable flux is particularly diflicult when highly reactive metals, such as uranium and alloys in which uranium is a predominant component, are to be protected.

I have discovered a new flux which is particularly adapted for use in melting uranium and uranium alloys.

The flux which I have found suitable to employ for the purposes above-mentioned is compounded in such manner that it possesses the following physical properties:

(1) It is fluid at temperatures below the melting point of uranium and commercial uranium alloys, i. e., it melts at approximately 9001000 C.; and

(2) It has a lower specific gravity when fluid than molten uranium or commercial uranium alloys.

I have found that a flux having such properties can be prepared by admixing in suitable proportions calcium fluoride, magnesium fluoride and uranium tetrafluoride. I have discovered that proportions of the various ingredicuts in this flux may be varied somewhat without substantially changing the desirable characteristics of my new and novel flux. I have found that the composition of a suitable flux, calculated on an anhydrous basis, may vary from about 35% to by weight calcium fluoride, 35% to 55% by weight magnesium fluoride, and 5% to 15 by weight uranium tetrafiuoride.

As a specific example of the preparation of a suitable flux and its use in preparing uranium-lead alloys, approximately 46% by weight of calcium fluoride, 46% by weight of magnesium fluoride, and 8% by Weight of uranium tetrafluoride were thoroughly mixed together. The flux was then placed in a graphite crucible and melted; thereafter uranium metal was charged into the crucible and melted, and then lead was added in an amount suificient to form the desired alloy. No substantial oxidation of the uranium occurred since the protective flux formed a molten layer resting upon and protecting the molten uranium.

It will be apparent to those skilled in the art to which this invention pertains that various modifications may be made without departing from the principles of the invention as disclosed herein, and thus it is not intended that the invention should be limited other than by the scope of the appended claims.

What is claimed is:

1. A flux composition for use with molten uranium and alloys that have a predominant content of uranium, said flux comprising about 35% to 55% by weight of calcium fluoride, about 35% to 55% by weight of magnesium fluoride, and about 5% to 15% by weight of uranium tetrafluoride.

2. A flux composition for use with molten uranium and alloys thereof that have a predominant content of uranium, said flux comprisingabout 46% by weight of calcium fluoride, about. 46% by weight of magnesium fluoride, and about 8% by weight of uranium tetrafluoride.

3. In a method of melting uranium and uranium-base alloys the step of adding a flux comprising about 35 to 55% by weight of calcium fluoride, about 35 to 55% of magnesium fluoride, and about 5 to 15% by weight of uranium tetrafluoride.

References Cited in the file of this patent UNITED STATES PATENTS 2,040,283 Swartz May 12, 1936 2,051,963 Monroe et al. Aug. 25, 1936 2,327,065 Reimers Aug. 17, 1943 OTHER REFERENCES International Critical Tables, vol. 4, page 62, published by McGraw-Hill Book Co., New York, N. Y. 

1. A FLUX COMPOSITION FOR USE WITH MOLTEN URANIUM AND ALLOYS THAT HAVE A PREDOMINANT CONTENT OF URANIUM, SAID FLUX COMPRISING ABOUT 35% TO 55% BY WEIGHT OF CALCIUM FLUORIDE, ABOUT 35% TO 55% BY WEIGHT OF MAGNESIUM FLUORIDE, AND ABOUT 5% TO 15% BY WEIGHT OF URANIUM TETRAFLUORIDE.
 3. IN A METHOD OF MELTING URANIUM AND URANIUM-BASE ALLOYS THE STEP OF ADDING A FLUX COMPRISING ABOUT 35 TO 55% BY WEIGHT OF CALCIUM FLUORIDE, ABOUT 35% TO 55% OF MAGNESIUM FLUORIDE, AND ABOUT 5 TO 15% BY WEIGHT OF URIANIUM TETRAFLUORIDE. 